There are great differences, too, in the roots of trees. In the fig, the robur, and the plane, they are numerous; in the apple they are short and thin, while in the fir and the larch they are single; and by this single root is the tree supported, although we find some small fibres thrown out from it laterally They are thick and unequal in the laurel and the olive, in which last they are branchy also; while in the robur they are solid and fleshy.[1] The robur, too, throws its roots downwards to a very considerable depth. Indeed, if we are to believe Virgil,[2] the æsculus has a root that descends as deep into the earth as the height to which the trunk ascends in the air. The roots of the olive, the apple, and the cypress, creep almost upon the very surface: in some trees they run straight and horizontally, as in the laurel and the olive; while in others they have a sinuous course—the fig for example. In some trees the roots are bristling with small filaments, as in the fir, and many of the forest trees; the mountaineers cut off these fine filaments, and weave with them very handsome flasks,[3] and various other articles.

Some writers say that the roots of trees do not descend below the level to which the sun's heat is able to penetrate; which, of course, depends upon the nature of the soil, whether it happens to be thin or dense. This, however, I look upon[4] as a mistake: and, in fact, we find it stated by some authors that a fir was transplanted, the roots of which had penetrated eight cubits in depth, and even then the whole of it was nut dug up, it being torn asunder.[5] The citrus has a root that goes the very deepest of all, and is of great extent; next after it come the plane, the robur, and the various glandiferous trees. In some trees, the laurel for instance, the roots are more tenacious of life the nearer they are to the surface: hence, when the trunk withers, it is cut down, and the tree shoots again with redoubled vigour. Some think that the shorter the roots are, the more rapidly the tree decays; a supposition which is plainly contradicted by the fig, the root of which is among the very largest, while the tree becomes aged at a remarkably early period. I regard also as incorrect what some authors have stated, as to the roots of trees diminishing[6] when they are old; for I once saw an ancient oak, uprooted by a storm, the roots of which covered a jugerum of ground.